The invention relates generally to the field of surgical instrumentation. More particularly, the invention relates to a lockable joint and a seal for use in conjunction with a lockable joint, especially a lockable ball-and-socket joint including a locking device having a piston, a pressure gas source, and an actuating device arranged for reversibly disconnecting the piston from the pressure gas source, these components including one or more high pressure seals. Such seals can relate especially to a high pressure gas seal for use in medical systems, the seal made at least in part of a material being resistant to a sudden drop in gas pressure, the material further having substantially stable performance at pressures between the high pressure and the low pressure, the material further having substantially stable performance below a low temperature and above a high temperature, and the material further having low porosity.
A lockable joint is known from U.S. Pat. No. 5,201,325. The lockable joint in this document can be actuated by pressured air that is delivered via a gas hose. As the gas pressure of pressurized gas in gas hoses usually is not sufficient to clamp the lockable joint safely, a pressure enhancing system is provided. Another lockable joint is known from U.S. Pat. No. 5,271,384. This lockable joint suffers from a clamping force that is not sufficient for many applications.
It is the problem of the present invention to mitigate problems associated with lockable joints known from prior art, and to provide seals capable of operating with and releasing high gas pressure.
The invention solves the problem with a lockable joint and a seal for a lockable joint, especially a lockable ball-and-socket joint that can include a locking device having a piston, a pressure gas source, an actuating device arranged for reversibly disconnecting the piston from the pressure gas source where the pressure gas source is a gas cartridge, and one or more seals facilitating the retention of gas between components. The problem of managing the gas pressure is solved according to specialized seals, especially seals for use in high-pressure gas-actuated medical systems, the seal made at least in part of a material being resistant to a sudden drop in gas pressure from a high pressure, e.g. more than 4 MPa (40 bar) to a low pressure, e.g. less than 0.11 MPa (1.1 bar), the material further having substantially stable performance at pressures between the high pressure and the low pressure, the material further having substantially stable performance below a low temperature, e.g. in particular embodiments, below −5° Celsius, or below −10° Celsius, or below −50° Celsius, and above a high temperature, e.g. in particular embodiments above 100° Celsius, or above 110° Celsius, or above 130° Celsius, and the material further having low porosity.
According to another aspect, there can be a method for making a seal for use in high pressure gas medical systems, comprising receiving a low-porosity material having a resistance to a sudden drop in gas pressure from a high pressure, e.g. more than 4 MPa (40 bar) to a low pressure, e.g. 0.11 MPa (1.1 bar), the material further having substantially stable performance at pressures between the high pressure and the low pressure, the material further having substantially stable performance below −5° Celsius, and in particular embodiments below −10° Celsius, and in other embodiments below −50° Celsius, and the material having substantially stable performance above 100° Celsius, and in particular embodiments above 110° Celsius, and in other embodiments above 130° Celsius. The method can further include forming a seal from the received material.
Usually, surgical retractors were hand-held instruments with multiple curved fingers used to hold open incisions during surgical procedures. The surgeon or an assistant would hook the fingers of the surgical retractor over the edge of an incision and apply tension to hold the incision open to provide access for the surgeon to internal bodily structures.
In approximately the last two decades, surgical retractors have been developed that are secured to a surgical table or other structure to allow retraction to be accomplished without the necessity of the surgeon or an assistant constantly holding the retractor.
For surgical retractors system according to the invention, a table rail post may be the foundation of a surgical retractor system. It provides an anchor for a frameset and other hardware onto which retractor instruments and other surgical instruments may be attached. A variety of retractor instruments with variably shaped retractor fingers are used in surgery to assist the surgeon in holding a surgical incision open or to move anatomical structures out of the way. The surgical retractor systems may use cam mechanisms or occasionally screw clamps to lock various members of the retractor system in position.
The surgical retractor system according to the invention may be a round stock retractor system and/or flat stock retractor system. Flat stock retractor systems suffer the limitation that because of the rectilinear nature of the various components, the components must be joined at substantially right angles in order to interconnect. Thus, the number of orientations in which flat stock retractor systems can be assembled is limited.
Round stock retractor systems generally are preferred because they allow for the interconnection of the various retractor system components at a variety of different angles because of the ability of the round stock parts of the system to rotate relative to one another and to clamp components.
Round stock retractor systems include various rod shaped parts that, initially, are connected together by screw-threaded type clamps. When screw-threaded type clamps are used, there might be a tendency for the screw clamps to deform the cylindrical members of the retractor system. Further, setting up, positioning and interconnecting the parts of the retractor system can require both hands, or possibly both hands of one individual, plus an assistant to assemble the system. Thus, cam lock or over center lock connection systems are preferred for mounting the surgical retractor to the first arm and/or for fixing the anchor element to the third arm.
The cam lock system may include two interconnected clamps that are configured to grip the rod shape retractor system members and that can be adjusted in rotation relative to each other. One rod shaped component is gripped in each clamp. The two interconnected clamps are activated by some sort of actuator such as a lever which then locks the two clamps to two rod-shaped members and also simultaneously locks the two clamps relative to each other in rotation. One disadvantage of this arrangement is that when the clamps are released, they are released completely from both rod-shaped members as well as in relative rotation, requiring that the retractor system be completely repositioned and realigned before re-clamping.
Surgical retractor systems are used to manipulate living tissue. The application of pressure to living tissue can damage cell structure or reduce blood flow to the tissue. Living tissue can be damaged by the application of pressure for too long a time. Therefore, it is recommended that during surgical procedures where mechanical retractors are used, periodically the retractors should be loosened or tension should be lessened on the retractors to allow increased blood flow to the tissue being retracted to prevent tissue hypoxia and possible necrosis. This requirement, along with the limitation of current retractor systems, creates a dilemma for the surgical team. The surgical teams can disconnect the surgical retraction system periodically but then be required to make complete adjustments of each surgical retractor to reconnect it. Alternately, the surgical team can leave the living tissue retracted under tension for long periods of time and risk tissue damage or necrosis to the tissues being retracted. Surgical team members tend to be reluctant to disconnect and then readjust the retractor system if the readjustment is time consuming or unwieldy or if readjustment will alter the carefully positioned relationship of anatomical structures.
Another issue that arises with current round stock surgical retractor systems arises from the fact that surgeons generally prefer to locate retractors so that they are providing retractive tension at an angle. Surgeons prefer this approach in order to move the retractor to one side of the field in which they must work so that the retractor does not interfere with their movements. When the surgical retractors are offset, quite often it is impossible to position the retractors so that the retractor is pulling completely linearly with relation to the long axis of the rod-shaped members. This imparts a torsional or rotational force to the clamps that are secured to cylindrical or rod shaped members of the retraction system. This force tends to cause the clamps of the retraction system to slip about the rods in a rotational fashion. A common response to this problem is to increasingly tighten the clamp that is applied to the rod-shaped member. Unfortunately, when tightened beyond a certain point, the clamp will tend to create deformation or galling of the rod shaped member to which it is clamped making it more difficult to adjust the system for future usage.
A problem that arises with currently available retraction systems is that when a retractor is fixed to the system by a current clamp the multi-axis joint created between components is completely locked so that the components joined are immovably fixed in all axes. Commonly, it is necessary for the surgeon or an assistant to increase or readjust retractions for certain activities. Adjusting retractions means that the surgeon or an assistant must loosen the clamp holding the retractor, reposition the retractor, and then reapply the clamp. Since prior art clamp releases completely from two rods and in rotation simultaneously, at least two hands are required to realign and retighten the system. This can be quite awkward as there is a period of time where tension on the retractor is reduced and tissues may move in an undesirable fashion when the tension is reduced.
Retractor frames generally include a first frame arm, a second frame arm and a locking device that may also be called clamping member and that secures the left frame arm and the right frame arm in a fixed position, so that a surgical retractor may secured to the left and right frame arms. In addition, retractor frames generally include a third support arm which can be secured to a surgical table rail post. Existing retractor frames suffer a number of limitations. For example, the clamping member that secures the right and left frame arms generally locks the right and left frame arms in position simultaneously. While convenient locking, the frame arms simultaneously can make it difficult to adjust the right and left frame arms independently of one another. In addition, in many prior art retractor frames the clamping member also secures the pivotable connection between the support arm and the clamping member at the same time that the right and left frame arms are secured, sometimes making it difficult to adjust the retractor frame as desired.
For the purpose of the following description a locking device may be any device that is arranged and adapted for immobilizing the swivel head relative to the socket. It is possible to provide two or even more locking devices. The locking device may provide a frictional locking with the swivel head. Alternatively, the locking device may be adapted for a positive locking or for a combination of both positive and frictional locking.
The actuating device may be any device that is adapted and arranged for allowing and interrupting a gas communication between the gas cartridge and the piston. For example, the actuating device may be a valve.
A gas cartridge may be a cartridge that contains a chemical composition or mixture of chemical compositions that is/are gaseous at ambient temperature of 20° C. and ambient air pressure of 1013 hPa. Alternatively, the gas cartridge contains a chemical composition that may be brought into contact with another chemical composition to react chemically so that such a gas is produced.
It is an advantage of the present invention that it is not necessary to provide an external source of pressurized air. Such an external source of pressurized air may not be available. Especially in hospitals, pressurized air systems are often contaminated with bacteria, so that this air must not be used for operation devices. As a further advantage, air hoses are no longer needed. Air hoses bear the risk of bursting and have to be checked regularly. They are also inconvenient to use and bear the risk of stumbling for personnel. It is another advantage that the gas cartridge may be a disposable gas cartridge. Disposable gas cartridges are easy to handle and to store, so that the lockable joint has a high reliability and availability. It is another advantage that the lockable joint can be actuated easily. A lockable joint is therefore advantageous for high precision applications.
In a preferred embodiment, that gas cartridge has an internal pressure of more than 4 MPa or 40 bar. In particular, the internal pressure is more than 5 MPa or 50 bar. This high pressure makes it possible to actuate the locking device directly by the piston. Standard air pressure systems used e.g. in hospitals usually have a pressure of below 0.7 MPa, so that the force of the piston has to be increased by a suitable device. These devices are error-prone and expensive. The use of a gas cartridge having an internal pressure of more than 4 PMa thus leads a lockable joint that is easy to manufacture, cheap and robust.
In a preferred embodiment, the gas cartridge contains less than 1000 g of gas. In particular, the gas cartridge contains less than 100 g of gas, e.g. 12 g to 50 g of gas. These kinds of gas cartridges are small and easy to handle, but contain a sufficient amount of gas for most applications of the lockable joint.
It is preferred that the gas cartridge contains carbon dioxide, pressurized air, pressurized nitrogen, pressurized nitrous oxide, pressurized noble gas, pressurized oxygen, or a mixture of two, three, four or five of the aforementioned substances. In particular, it is preferred that the gas cartridge contains carbon dioxide and may therefore be called a carbon dioxide cartridge. Carbon dioxide is non-toxic, easy to manufacture and harmless to handle. It is an advantage, that carbon dioxide is a liquid at room temperature of 20° C., if the pressure is above 5.8 MPa. As a liquid, carbon dioxide has a high density so that even small carbon dioxide cartridge can store a significant amount of carbon dioxide.
It is preferred that the carbon dioxide cartridge contains sterile carbon dioxide. Used carbon dioxide from a sterile carbon dioxide cartridge may be released into the ambient air even in an operating room.
Seals used with the gas cartridge, conduits directly or indirectly to the gas cartridge, the actuating device, and/or other components, are designed to withstand high-pressure gases and various operating environments used in conjunction with or related to aspects herein.
It is preferred that the lockable joint has a main body, the main body comprising the socket in the locking device, the locking device having a fixing element that is received in the main body, and the piston being arranged for pressing the fixing element against the swivel head. It is particularly advantageous that the piston and the fixing element are connected, such that moving the piston in a piston working direction leads to movement of the fixing element in a fixing working direction, whereby the piston working direction is parallel to the fixing element working direction. This yields a particularly advantageous flux of force.
It is a particular advantage if the piston and the fixing element are directly coupled, such that moving the piston by pre-determined pistons leads to a movement of the fixing element by the same pre-determined distance. That is, no force increasing mechanism is required. That leads to an easy to manufacture lockable joint. In particular, the piston is arranged for pressing against the swivel head. The contacting part may be called fixing section.
In an preferred embodiment, the main body comprises a cylinder, the cylinder having an inlet opening, the piston being moveably received in the cylinder and comprising a fixing section for pressing against the swivel head, the fixing section being located opposite the inlet opening. In this embodiment, gas streaming thru the inlet opening into the cylinder pushes the piston towards the swivel head thus pressing its fixing section against it. The socket is arranged such that the swivel head presses against the socket when the fixing section presses against the swivel head. Thus, the swivel head is locked between the socket and the fixing section. As the piston is snugly received in the cylinder and as the socket is rigidly mounted to the main body, the swivel head is locked, i.e. tightly fixed and clamped, to the main body. If a high gas pressure is provided, e.g. 6 MPa, a clamping force of more than 4000 N is easily achievable.
In a preferred embodiment, the main body comprises a gas cartridge retainer for changeably receiving the gas cartridge. It is then possible to use disposable or one-way gas cartridges that are easily available at low prices. Further, it is possible to use the lockable joint in places where a pressurized air system is not available. Examples are developing countries or remote places.
It is preferred that the fixing element, in particular the fixing section of a piston, is arranged for contacting the swivel head in a fixing element contact area that is a ring-shaped and has a ring width of less than 1 mm. This yields a particularly strong clamping force that the locking device exerts on the swivel head, as a small ring width leads to a high pressure that in turn causes an elastic deformation of the swivel head.
In a preferred embodiment, the fixing element is arranged for frictional locking between the fixing element and the swivel head. This leads to an easy to manufacture and robust lockable joint. The contact section area may be segmented. To achieve this, the fixing element, e.g. the fixing section of the piston, may be provided with clearances or cuts. These clearances may also be arranged to enable cleaning or the lockable joint, in particular the swivel head, after use or to disinfect the lockable joint.
It is preferred that the swivel head has swivel head outer diameter and contacts the fixing element, e.g. the fixing section of the piston, in a ring-shaped swivel head contact area that is larger than 0.94 times the swivel head outer diameter.
It is preferred that the first arm has an arm longitudinal axis and the contact area outer diameter and the arm longitudinal axis form a substantially constant effective angle of less than 20°. In particular, it is preferred that the effective angle is larger than 1°.
To allow for as many lock-and-release cycles, it is preferred that the gas cartridge has a gas cartridge outlet opening, the cylinder and a gas cartridge being in gas communication via a gas conduct between the gas cartridge outlet opening and the cylinder inlet opening, wherein the gas conduct has an volume of less than 1000 mm3, in particular less than 500 mm3. To maximize the number of lock-and-release cycles, it is also preferred that the piston has a stroke of less than 2 mm, and in particular less than 1 mm.
To provide for a strong clamping force, the piston preferably has a piston diameter of more than 20 mm.
According to another aspect, the invention relates to a lockable joint assembly that comprises (a) a lockable joint according to the first aspect of the invention, (b) a second arm having a second swivel head, (c) a second socket head being pivotably mounted to the second socket, (d) a second locking device arranged for locking the second swivel head with respect to the second socket, the second locking device having (i) a second piston disconnectably connected to the gas cartridge and (ii) a second actuating device arranged for reversibly disconnecting the second piston from the gas cartridge. For the sake of easy handling, the second arm is preferably arranged opposite the first arm.
To fix the lockable joint to an anchor element, the lockable joint preferably comprises (a) a support arm having a support swivel head, (b) a support arm socket, pivotably mounted to the support arm socket, and (c) a support arm locking device arranged for locking the support arm swivel head relative to the support arm socket, the support arm locking device having (i) a support arm piston interruptibly connected to the gas cartridge and (ii) a support arm actuating device arranged for reversibly disconnecting the support arm piston from the gas cartridge.
According to still a further aspect, the invention relates to a surgical retractor system, comprising (a) a lockable joint assembly according to the invention, (b) an anchor element adapted for mounting to an operating table, the anchor element being releasable mounted to the support arm, the first arm being adapted to act as a frame element for receiving at least one surgical retractor.
The surgical retractor frame of the present invention is adapted to be anchored to a surgical post secured to a surgical table rail, or to another fixed structure, to allow the application of surgical retractors that are used for the retraction of anatomical structures.
The surgical retractor frame of the present invention may include a main body in form of a control hand piece, a support arm and two frame arms, i.e. the first arm and the second arm.
The support arm and two frame arms (first arm and second arm) can be articulated with the control hand piece via ball joints. Each ball joint supports one of the support arms and the two frame arms. Each ball joint is independent lockable and releasable at any location within its articular range. That is, each ball joint can be independently released, adjusted and secured independent of the other two ball joints.
The independent gas pressure driven locking mechanism of the present invention is operated by a pressurized gas source in form of gas cartridge, e.g. a small pressurized gas cylinder containing pressurized gas such as carbon dioxide, nitrogen, or compressed air.
In one exemplary embodiment, the pressurized gas supply is provided in a small carbon dioxide cartridge or cylinder. The carbon dioxide cartridge is contained within the control hand piece of the present invention. The carbon dioxide cylinder is intended to be replaced with each use of the surgical retractor frame. For example, the control hand piece may have a generally cylindrical chamber into which the compressed gas cylinder may be placed. Once the gas cylinder is placed in the chamber, a screw for carding the gas cylinder may be inserted behind the gas cylinder and tightened until the gas cylinder is pierced by a trocar or hollow needle. The gas cylinder is simultaneously sealed to the control hand piece.
The main body or control hand piece may further include an independent push button or other valve actuator to operate each individual spherical ball joint. The support arm locking device operates the ball joint for the support arm.
In one aspect of the invention, the operation of the support arm locking device is such that the support arm is locked by pressurized gas pressing the support arm piston against the swivel head, i.e. a spherical member, of the ball joint except when the actuating device, e.g. a push button, is depressed. The support arm locking device is structured such that when its push button is depressed, pressurized gas acting against the support arm piston is released while pressurized gas is sealed off within the gas cartridge so that gas is not vented constantly. The actuating device for the first arm operates the first arm, i.e. the right frame arm, and the second locking device operates the second arm, i.e. the left frame arm. The ball joints are arranged so that some tension is kept on the spherical member by the piston, even when the gas pressure is released. This provides tension so that the frame arm may be adjusted into a desired position without “flopping” in response to gravity.
In one aspect of the invention, the pressurized gas cylinder has a fail-safe pressing release so that if a hospital staffer mistakenly places the surgical retractor frame in an autoclave for sterilization with the gas cylinder still installed, the gas cylinder will vent safely, thus preventing the risk of an explosion in the autoclave.
In one aspect of the invention, the pistons which bear with their fixing sections against the ball joint spheres have a piston seal including a stainless steel spring within the piston seal. O-rings or pistons without seals may also be utilized.
In a preferred embodiment, the seal(s) (or O-rings) are high pressure gas seal(s) made at least in part of a material having a resistance to a sudden drop in gas pressure, the material further having substantially stable performance at pressures between a low pressure and a high pressure, the material further having substantially stable performance below a low temperature and above a high temperature, and the material further having low porosity.
The compressed gas that is used to operate the pistons in the surgical refractor frame may be supplied at a pressure between about 200 and 350 pounds per square inch. In one aspect of the invention, the system operates at pressures of roughly 300 pounds per square inch.
It is notable that the piston travel in the surgical retractor frame may be very short; on the order of less than one millimeter. The fit of the piston within the cylinder is quite tight so that the piston maintains tension on the sphere of the ball joint even when the pressure on the piston is released. The piston and sphere of the ball joint may be made of a metallic material such as, for example, Nitronic 60, Galltough™, or V4A™ steel.
The locking devices may comprise dual function push button valves that both vent pressure from the respective piston and cylinder and seal the gas passages or ducts from the pressurized gas source simultaneously.
The control hand piece may include an ergonomic hand grip. The body of the control hand piece may be formed of, for example, stainless steel such as 400 series stainless steel or V4A steel.
In one embodiment of the invention, the first and second, e.g. the left and right, frame arms and the support arm may be tubular structures rather than the more conventional solid bars. This lightens the structure of the surgical retractor frame without significantly sacrificing strength. The spheres of the ball joints may be solid or hollow. All of the metallic parts of the present invention may also be formed of materials such as titanium or stainless steel.
The gas cartridge may be supplied in a sterile or a non-sterile state. When non-sterile cartridges are used, a sterile sleeve may be used to maintain a sterile field in the operating room to allow for cartridge exchange, if needed, during a surgical procedure.